基于rDNA-ITS的中国外来香蕉穿孔线虫种群的系统发育分析

为揭示传入中国的香蕉穿孔线虫群体间的遗传差异,分析其亲缘和进化关系,明确中国香蕉穿孔线虫的来源和传入途径,分别扩增了多雌繁殖群体和相应种群的单雌繁殖群体后代rDNA-ITS,对扩增产物进行测序,通过序列比对分析其遗传变异,并构建系统发育树研究其亲缘和进化关系。结果表明:供试香蕉穿孔线虫20个种群的rDNA-ITS序列大小为705~713bp,序列同源性比较高,相似性在95%以上,序列变异率为0~7.5%;各群体ITS1和ITS2序列大小分别为273~276bp和151~152bp,各种群间的序列相似性分别达到98.58%和98.35%以上;单雌繁殖群体与相应的多雌繁殖群体的序列相似性非常高,有8个种群的2个繁殖群体序列相似性达到100%,其他种群的2个繁殖群体序列相似性达97%以上;基于ITS序列构建穿孔属线虫的系统发育树说明,所有香蕉穿孔线虫聚在一个大枝,分成4小分枝,其中寄主为红掌的RsW种群单独聚为一枝,遗传距离较远,寄主为绿宝石的RsH遗传距离相对其他种群也较远,寄主分别为天鹅绒竹芋和孔雀竹芋的RsP和RsS种群的遗传距离则相对较近,这说明传入中国的香蕉穿孔线虫种群可能直接来源是欧洲的竹芋科和天南星科观赏植物,而前者的最初来源可能是苏丹的香蕉,后者的最初地理来源较复杂。

Phylogenetic analysis of exotic Radopholus similis in China based on rDNA-ITS sequences

To demonstrate genetic divergence of different populations of exotic Radopholus simils in China,analyze their phylogenetic relationship,and provide scientific proof for the origin of these populations,the published universal primers were used to amplify the rDNA-ITS sequences of progeny of single and 25 females,respectively,from 20 populations of R.similis.The amplified products were sequenced,blasted and aligned with public submitted sequences and phylogenetic tree was then constructed.The rDNA-ITS sequenced was 705-713 bp in length,and showed high similarity (≥95％) among different populations,with a divergence of 0-7.5 ％.The rDNA-ITS1 and ITS2 were 273-276 bp and 151-152 bp in length,with sequences similarity ≥98.58％ and ≥98.35 ％,respectively.The sequences alignment results showed that the ITS sequences had a very high similarity between the progeny of single female and multiple females in the same population,showing 100％ sequence identity in 8 populations and ≥97％ similarity in the other populations.In addition,the phylogenetic tree with Pratylenchus coffeae as outgroup showed that all R.similis populations were clustered together,but with 4 small branches.Among them,Anthurium andraeanum population RsW was clustered in a single branch,Philodendron sp.population RsH had a longer genetic distance with other members in the same branch,but Calathea zebrin e population RsP and C.makoyana RsS had a shorter genetic distance.The results indicated that the R.similis populations in China mainly came from the European Marantaceae and Araceae ornamentals,and the primary origin for the former was banana in Sudan and was complicated for the lat-ter.